A Refined Murine Model of Post-sepsis Cognitive Impairment for Investigating Mitochondrial Abnormalities and Human ApoE4 Gene Polymorphisms

摘要 脓毒症是一种由感染引发的危及生命的疾病， 炎症现在每年有超过170万败血症幸存者出院，其中大多数人 他们中的许多人报告说，由于相当长的长期功能障碍，称为慢性危重病， 包括出院后的肌肉无力和认知障碍。我们以前开发了一个 具有ICU样复苏程序的临床相关小鼠败血症存活模型，使我们能够 评估脓毒症恢复后的长期肌肉质量和功能。我们的研究表明， 败血症存活小鼠表现出明显的骨骼肌无力。这些败血症幸存者的骨骼肌 小鼠还显示出严重的线粒体结构和功能缺陷。与肌肉功能障碍相反， 对于脓毒症幸存者的认知功能障碍知之甚少。尽管有几项已发表的研究使用 对于这个问题的实验室动物模型，由于几个限制，他们的结果仍然是不确定的; 1）认知 通过应激性游泳迷宫测试评估损伤，脓毒症幸存者表现不佳， 肌无力; 2）使用具有人为坏死的外科脓毒症模型， 炎症;以及3）缺乏抗生素治疗和缺乏脓毒症恢复的确认，从而 关注于“脓毒症期间”而不是“脓毒症后”的功能障碍，所有这些都限制了当前的研究。重要的是所有 这些局限性在我们的上述败血症存活小鼠模型中得到解决， 从脓毒症中恢复，允许脓毒症后有足够的时间（4周或更长）来研究长期效应，以及 消除了外科手术，以避免人为的坏死和炎症。因此，我们精心设计的败血症- 肌无力存活小鼠模型可能是研究后 脓毒症长期认知障碍我们的主要假设是这个脓毒症幸存者模型将表现出长期的- 认知障碍我们还假设ApoE 4基因多态性，最常见的AD- 易感基因型，赋予更高的风险发展认知功能障碍后生存败血症。 此外，我们假设线粒体异常参与了这种脓毒症后认知功能障碍， 损伤为了检验这些假设，我们将追求两个具体目标。(1)为了测试野生型 小鼠在脓毒症后发生长期认知障碍;和（2）为了测试突变小鼠是否 携带人类ApoE 4基因多态性者发生认知功能障碍的风险更高 败血症后

ABSTRACT Sepsis is an infection-initiated life-threatening medical condition accompanied by severe whole-body inflammation. Over 1.7 million sepsis survivors are now discharged from the hospital annually, and a majority of them report reduced quality of life due to considerable long-term dysfunction, called chronic critical illness, including muscle weakness and cognitive impairment after hospital discharge. We previously developed a clinically relevant murine sepsis-survivor model with an ICU-like resuscitation procedure that enables us to evaluate long-term muscle quality and function after recovery from sepsis. Our studies demonstrated that sepsis-survivor mice exhibit significant skeletal muscle weakness. Skeletal muscles from these sepsis-survivor mice also show profound mitochondrial structural and functional defects. In contrast to muscle dysfunction, little is known for cognitive dysfunction in sepsis survivors. Although there are several published studies using laboratory animal models for this issue, their results remain inconclusive due to several limitations; 1) cognitive impairment being assessed by stressful swimming maze tests which sepsis survivors perform poorly due to muscle weakness; 2) use of surgical sepsis models with artifactual necrosis and resulting systemic inflammation; and 3) the lack of antibiotics treatment and the lack of confirmation of sepsis recovery, thereby focusing on dysfunction “during sepsis” rather than “post-sepsis”, all limit current research. Importantly, all these limitations are resolved in our above-mentioned sepsis-survivor mouse model that confirms complete recovery from sepsis, allows sufficient duration (4 weeks or longer) after sepsis to study long term effects, and eliminates surgical procedures to avoid artifactual necrosis and inflammation. Thus, our well-refined sepsis- survivor mouse model for muscle weakness can potentially be an appropriate animal model to investigate post- sepsis long-term cognitive impairment. Our major hypothesis is that this sepsis-survivor model will exhibit long- term cognitive impairment. We also hypothesize that ApoE4 gene polymorphism, the most common AD- susceptible genotype, confers a higher risk of developing cognitive dysfunction after surviving sepsis. Additionally, we hypothesize that mitochondrial abnormalities are involved in such post-sepsis cognitive impairment. To test these hypotheses, two Specific Aims will be pursued. (1) To test whether wild type mice develop long-term cognitive impairment after sepsis; and (2) To test whether mutant mice carrying the human ApoE4 gene polymorphism have a higher risk of developing cognitive impairment after sepsis.